How Should a Nonfunctioning Pituitary Macroadenoma be Monitored After Debulking Surgery?

Yona Greenman; Naftali Stern

Disclosures

Clin Endocrinol. 2009;70(6):829-832. 

In This Article

Long-term Monitoring

The long-term follow-up strategy is based on the slow-growing nature of NFPA and on the reported rates of recurrence or tumour remnant progression. The calculated tumour volume doubling time (TVDT) is variable and ranges from 0·8 to 27·2 years.[16] Patients with TVDT under 5 years were younger (50 ± 15 years) than those with TVDT over 5 years (69 ± 7 years).[17] The true recurrence/progression rate of NFPA is difficult to assess because of selection bias (more aggressive tumours being referred to radiotherapy)[18] and variable surveillance methods. Most series are retrospective in nature and lack a pre-established protocol for imaging intervals. Tumour growth may be detected earlier, at an asymptomatic stage, through serial MRI imaging, or later, when patients present with mass-related symptoms. Despite these caveats, patients in whom complete tumour resection has been achieved have, in general, a low risk for recurrence, whereas those with residual tumours have high long-term progression rates (13% and 41%, respectively).[5] Longer follow-up duration is associated with increased detection of recurrence/progression.[6] The mean time for detection of tumour progression varies between 2·2 and 7·5 years ( Table 1 ), ranging from 6 months to 20 years. Some clinical aspects, such as young age[3] and extent of suprasellar extension in the residual tumour,[19] have been associated with a higher risk of tumour enlargement. This may indicate the need for more careful surveillance for these patients. Nevertheless, in general, our ability to predict tumoural biological behaviour is poor. Morphological features in the pathologic specimen, such as cytological atypia, and presence of mitoses do not reliably reflect tumour aggressiveness. Similarly, markers of cell proliferation, such as Ki-67, PCNA and p53, do not consistently correlate with tumour invasiveness or recurrence.[20,21] Therefore, we perform MRI yearly for the first 3-5 years after surgery in all patients, for the detection of more rapidly growing tumours. The detection of an increase in tumour mass not leading to prompt re-operation will require a repeat imaging study at an earlier time. In the absence of such progression, however, imaging intervals may be then spaced to every 2 years and later on to every 3 years, as at this point we are dealing with stable or very slow growing tumours. Technical aspects of MRI interpretation and tumour size evaluation should be established a priori and standardized to allow for accurate comparisons over time. Another aspect to be emphasized is the need to compare the most current imaging study not only with the previous, but also with earlier studies, as this is the only way to reliably detect small size changes over time. Visual field testing should be performed generally every 12 months, especially when the tumour margins are in relative proximity to the optic chiasm, or in between imaging studies in other instances. More frequent visual assessment is needed for tumours quite adjacent to the optic chiasm, as appearance of new or deterioration of existing visual field defects is reported in nearly half of the patients in whom tumour growth occurs during conservative follow-up.[22] Pituitary function should also be assessed on a yearly basis, as it may become compromised with tumour growth.

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